Oracle

SelectDeptno,job,avg(SAL) fromEmpGroup byDeptno,jobOrder byDeptno;SelectDeptno,job,avg(SAL) fromEmpGroup byCube (deptno,job)Order byDeptno;SelectDeptno,job,sum(SAL),Grouping(DEPTNO),Grouping(Job) fromEMPGroup byRollup (deptno,job)Order

GrammarSelect ... from tablewhere filter conditionsThe constraints of the root node of start with query resultsConnect by connection conditions;ExampleCREATE TABLE Test (ID number,parent_id number,Name VARCHAR2 (100));Assume that the root node ID is

Oracle starts from scratch and is overwhelmed. The best way to master a skill is to learn how to use it, then learn it in depth, first look, then technology.One, what is a database? Why do I need a database?A database is essentially a list of

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--display dates in a specific formatSelectEname,to_char (HireDate,'YYYY "Year" MM "month" DD "Day"') fromEMP;--Exclude Duplicate rowsSelect distinctDeptno,job fromEMP;SelectDeptno,job fromEMP;--handling NULL using the NVL functionSelectename,

--① Creating a directoryCreate or ReplaceDirectory Oracle_test as 'd:\\testtmp'; --② Stored ProceduresCreate or Replace procedure proc(Stuid Tb_student.stuid%type, Stuname tb_student.stuname%type, stuage tb_student.stuage%Type ascou Number;--Insert

Declare --Defining VariablesV_enamevarchar2(5); V_sal Number(7,2); begin --Executive SectionSelectEname,sal intoV_ename,v_sal fromEmpwhereEmpno=&AA; --Display the user name in the consoleDbms_output.put_line ('the user name

Flash back Technology (flashback) starts with a 9i version of the flashback query, and is applied in the 10g version, and is enhanced in 11g11g Flash back technology projects:Flash Back Database technologyEnabling the database to roll back quickly

1. Turn on 10046 trace eventsAlter session SET Events ' 10046 Trace name Context forever, Level 12 ';If you want to make it easier to identify the trace file, you can set the trace's identity before opening the eventAlter session set

1. Subqueries Solve the problem: When a simple query query does not reach the results, you can use a subquery to enrich the conditions of the query to achieve the purpose of displaying the results.The format of a subquery: include it with a

The first step: the installation of Oracle services, two unpacking, respectively extracted after merging into a folder, click EXE installation (if you encounter path problem during installation, directly ignore it)Step two: Use SQLPlus to test

1. Start simpleDECLAREName VARCHAR2 (20);BEGINSelect First_Name into name from Hr.employees where employee_id=&no;Dbms_output.put_line (name);EXCEPTIONWhen No_data_found ThenDbms_output.put_line (' The employee does not exist! ');END;/2.

Stop replicate times error:opening port for Replicat myrep (TCP/IP error:connection refused).Start replicate times Replicat xxx is already running.The reason is that the corresponding xxx.pcs file in the Dirpcs directory is not deleted

Create a tablespace in oracle and assign user permissions. 1. create temporary tablespaces (temporary tablespaces are mainly used for sorting operations in the database [such as creating indexes, order by and group by, distinct,

Oracle Database 10g basic learning (1), oracledatabase Oracle was overwhelmed from scratch. To master a skill, the best way is to first learn how to use it, and then study it in depth. First, there will be technology.   1. What is a database? Why

ORA-00392ORA-00312 log clearing fault, ora00392ora00312 Recently encountered a ORA-00392 after restoring the Oracle database open: log 3 of thread 1 is being cleared, operation not allowed, its literal meaning is that the log file is being cleared,

Detailed tutorial on installing and configuring Oracle databases on CentOS, centosoracle I. basic configuration 1. Remaining hard disk space: 10 Gb or aboveAlthough the 10 Gb Installation File of Oracle is only over 800 MB, the installed oracle +

Describes the usage of data dictionaries and related SQL queries in Oracle databases. Oracle Data Dictionary Overview A database is a collection of data. The database maintains and manages the user data, so where are these user data tables, what is

Oracle learning notes series ------ basic oracle operations and basic oracle operation statements   -- CREATE a table create table employee_souvc (id NUMBER (4), name VARCHAR2 (20), gender CHAR (1), birth DATE, salary NUMBER (6, 2 ), job VARCHAR2 (30

Oracle client ORA-12541: TNS: no listeners, ora-12541tns 1. Question description: If you are setting the oracle client to add a local network service, you may see the dialogue that show you the message (Oracle client ORA-12541: TNS: No listener ).